U.S. patent application number 10/462936 was filed with the patent office on 2003-11-13 for laser thermometer.
Invention is credited to Hollander, Milton Bernard, McKinley, William Earl.
Application Number | 20030210732 10/462936 |
Document ID | / |
Family ID | 29408243 |
Filed Date | 2003-11-13 |
United States Patent
Application |
20030210732 |
Kind Code |
A1 |
Hollander, Milton Bernard ;
et al. |
November 13, 2003 |
Laser thermometer
Abstract
Method and apparatus are provided for visibly outlining the
energy zone to be measured by a radiometer. The method comprises
the steps of providing a laser sighting device on the radiometer
adapted to emit more than two laser beams against a surface whose
temperature is to be measured and positioning said laser beams
about the energy zone to outline said energy zone. The apparatus
comprises a laser sighting device adapted to emit more than two
laser beams against the surface and means to position said laser
beams about the energy zone to outline said energy zone. The laser
beams may be rotated about the periphery of the energy zone. The
laser beams may be rotated about the periphery of the energy zone.
In another embodiment, a pair of laser beams are projected on
opposite sides of the energy zone. The laser beams may be further
pulsed on and off in a synchronized manner so as to cause a series
of intermittent lines to outline the energy zone. Such an
embodiment improves the efficiency of the laser and results in
brighter laser beams being projected. In yet another embodiment, a
primary laser beam is passed through or over a beam splitter or a
diffraction grating so as to be formed into a plurality of
secondary beams which form, where they strike the target, a pattern
which defines an energy zone area of the target to be investigated
with the radiometer. Two or more embodiments may be used together.
A diffraction device such as a grating may be used to form multiple
beams. In a further embodiment, additionally laser beams are
directed axially so as to illuminate the center or a central are of
the energy zone.
Inventors: |
Hollander, Milton Bernard;
(Stamford, CT) ; McKinley, William Earl;
(Stamford, CT) |
Correspondence
Address: |
William A. Drucker
Suite 800
1901 L Street, N.W.
Washington
DC
20036-3506
US
|
Family ID: |
29408243 |
Appl. No.: |
10/462936 |
Filed: |
June 17, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10462936 |
Jun 17, 2003 |
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10243073 |
Sep 13, 2002 |
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10243073 |
Sep 13, 2002 |
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09843927 |
Apr 30, 2001 |
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6540398 |
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09843927 |
Apr 30, 2001 |
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09145549 |
Sep 2, 1998 |
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6267500 |
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09145549 |
Sep 2, 1998 |
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08848012 |
Apr 28, 1997 |
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5823679 |
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08764659 |
Dec 11, 1996 |
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08617265 |
Mar 18, 1996 |
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5727880 |
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08617265 |
Mar 18, 1996 |
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08348978 |
Nov 28, 1994 |
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5524984 |
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08348978 |
Nov 28, 1994 |
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08121916 |
Sep 17, 1993 |
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5368392 |
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Current U.S.
Class: |
374/120 |
Current CPC
Class: |
G01J 5/08 20130101; G01J
5/02 20130101; G01J 5/0808 20220101; G01J 5/07 20220101; G01J
5/0265 20130101; G01J 5/084 20130101; G01J 5/0859 20130101; G01J
5/0896 20130101 |
Class at
Publication: |
374/120 |
International
Class: |
G01K 001/16 |
Claims
We claim:
1. A method for outlining an energy zone on a surface whose
temperature is to be measured using a radiometer, said method
comprising the steps of providing a laser device associated with
said radiometer, and causing said device to emit a plurality of at
least three laser beams towards said surface to strike said surface
at individual mutually spaced locations serving at least to outline
said entire energy zone.
2. The method of claim 1, wherein said method further comprises the
steps of causing said sighting device to project a laser beam
towards said surface, and subdividing said laser beam with a beam
splitter means to provide said more than two of laser beams.
3. A method for outlining an energy zone on a surface whose
temperature is to be measured using a radiometer, said method
comprising the steps of providing a laser device associated with
said radiometer, causing said laser device to emit at least one
laser beam, passing said at least one laser beam across a
diffraction grating to subdivide said beam into a plurality of at
least three laser beams, and directing said plurality of at least
three laser beams towards said surface to strike said surface at
individual mutually spaced locations serving at least to outline
said energy zone.
4. Apparatus, for use in conjunction with a radiometer, for
outlining an energy zone on a surface whose temperature is to be
measured using said radiometer, said apparatus comprising; a laser
sighting device co-operating with said radiometer and means for
emitting a plurality of at least three laser beams to strike said
surface at individually spaced apart locations serving to outline
said energy zone.
5. The apparatus of claim 4 including a sighting device and a beam
splitter diffraction means, and wherein said sighting device
projects at least one primary laser beam towards said surface, and
wherein beam splitter means are disposed between said device and
said surface to be struck by said at least one primary laser beam
and to subdivide said at least one primary laser beam into a
plurality of secondary laser beams.
6. Apparatus, for use in conjunction with a radiometer, for
outlining an energy zone on a surface whose temperature is to be
measured using said radiometer, said apparatus comprising a laser
sighting device co-operating with said radiometer, said sighting
device projecting at least one primary laser beam towards said
surface, and a diffraction grating disposed between said device and
said surface to be struck by said at least one primary laser beam
and to subdivide said laser beam into a plurality of at least three
secondary laser beams to strike said entire surface at individually
spaced apart locations serving to outline said entire energy
zone.
7. The apparatus of claim 4 in combination with a radiometer, said
radiometer being positioned laterally of said laser sighting
device.
8. The apparatus of claim 4, in combination with a radiometer, said
radiometer being positioned between said plurality of laser beams
emitted by said laser sighting device.
9. The apparatus of claim 5 in combination with a radiometer, said
radiometer being positioned on the central longitudinal axis of
said secondary laser beams downstream of said diffraction
means.
10. A method of measuring and displaying surface temperature in a
defined energy zone with a radiation pyrometer comprising:--A)
pointing a heat responsive pyrometer in the direction of said
energy zone on said surface;--B) directing a plurality of at least
three laser beams from a laser generator system to impinge a
plurality of at least three visible spots on said zone to identify
a closed figure which includes most of said zone where temperature
is to be measured; and--C) locating said pyrometer and said
generator as a functional combination to direct said beams in
essentially the direction of the pyrometer pointing towards said
energy zone so that said spots outline said zone measured by said
pyrometer.
11. A method of generating beams according to claim 10 in which at
least one beam from said generator is split by a diffraction
device.
12. Apparatus for measuring and displaying temperature across a
surface in an energy zone comprising: a radiation pyrometer
co-operating with a laser beam generator; means directing heat
responsive elements of said pyrometer along a path between said
surface and said pyrometer; and means directing a plurality of
laser beams from said generator along an essentially parallel path
to said path between so as to display a visible laser spot pattern
around said zone from which said pyrometer measures
temperature.
13. Apparatus according to claim 12 including means to produce
plural laser beams from said generator.
14. Apparatus according to claim 13 in which said means to produce
is a diffraction device.
15. A laser sighting device for outlining an energy zone to be
measured by a radiometer when measuring the temperature of a
surface, said device including: means projecting more than two
laser beams toward said surface; means causing said laser beams to
outline the periphery of said energy zone.
16. A laser sighting device for identifying and defining an energy
zone to by measured by a radiometer when measuring the temperature
of a surface, said device including: means to project at least one
laser beam toward said surface; and means rotating said projecting
means so as to cause said beam to travel about the periphery of the
energy zone on said surface so as to identify and define the energy
zone.
17. A laser sighting device for visibly outlining an energy zone to
by measured by a radiometer when measuring the temperature of a
surface, said device generating more than two laser beams adapted
to project towards said surface on different sides of said energy
zone so as to outline substantially the entire periphery
thereof.
18. A laser sighting device for identifying and defining the center
and periphery of an energy zone to be measured by a radiometer when
measuring the temperature of a surface, said device including:
means for projecting more than two laser beams towards said
surface; and means for causing said laser beams to identify and
define both the center and substantially the entire periphery of
said energy zone.
19. A laser sighting device for identifying the center of an energy
zone on a surface and for outlining the periphery of said energy
zone, said device adapted to be used in conjunction with a
radiometer when measuring the temperature of said surface, said
device including: means for projecting at least one laser beam
toward said surface to identify the center of said energy zone; and
means for projecting more than two other laser beams toward said
surface to outline the periphery of said energy zone on said
surface.
20. The laser sighting device of claim 19 wherein said means for
projecting said other laser beams is caused to rotate said other
laser beams to travel about and outline the periphery of said
energy zone on said surface.
21. Apparatus for use in conjunction with a radiometer for visibly
identifying an energy zone on a surface whose temperature is to by
measured using said radiometer, said apparatus comprising a laser
sighting device for emitting laser beams against said surface and
said beams being positioned to be divergent with respect to the
energy zone to outline visibly the periphery of said zone.
22. Apparatus as claimed in claim 21 wherein said laser sighting
device emits more than two laser beams against said surface.
23. Apparatus for use in conjunction with a radiometer for
identifying the extent of an energy zone whose temperature is to be
measured using said radiometer, said apparatus comprising a laser
sighting device co-operating with said radiometer and arranged to
emit a laser beam toward said energy zone and mirror means
modifying said laser beam and directing said modified beam towards
the energy zone to illuminate a circular line about said energy
zone.
24. Apparatus as claimed in claim 23 wherein said means for
modifying and directing said laser beam are mechanical means.
25. Apparatus for use in conjunction with a radiometer for
identifying the extent of an energy zone whose temperature is to be
measured using said radiometer, said apparatus comprising a laser
sighting device co-operating with said radiometer and arranged to
emit a circular beam along the axis of the radiometer towards the
energy zone to form an illuminated ring at said energy zone
defining the extent of the zone to be measured.
26. Apparatus for use in conjunction with a radiometer for
identifying the extent of an energy zone whose temperature is to be
measured using said radiometer, said apparatus comprising a laser
sighting device co-operating with said radiometer for emitting
laser beams toward said energy zone to mark the edge and the center
of an area of said zone which is to be measured.
27. Apparatus for use in conjunction with a radiometer for visibly
outlining an energy zone on a surface whose temperature is to be
measured using said radiometer, said apparatus comprising a laser
sighting device for emitting more than two laser beams against said
surface and means for positioning said laser beams about the energy
zone to outline visibly the periphery of said energy zone.
28. Apparatus as claimed in claim 27 wherein said means for
positioning said laser beams are arranged to outline visibly only
the periphery of said energy zone.
29. Apparatus, as claimed in claim 28 wherein said means for
positioning said laser beams comprises a mirror, and means for
positioning said mirror for receiving and reflecting said laser
beams against said surface to outline said energy zone.
30. A method for identifying the extent of a radiation zone on a
region whose temperature is to be measured, using a radiometer,
said method comprising the steps of: providing a sighting device
for use in conjunction with said radiometer, said device including
means for generating a laser beam; splitting said laser beam into
more than two components; and directing said components toward said
region to identify substantially the entire extent of said
radiation zone.
31. A method for identifying the extent of a radiation zone on an
area whose temperature is to be measured using a radiometer, said
method comprising the steps of: providing a sighting device for use
in conjunction with said radiometer, said device including means
for generating a laser beam; splitting said laser beam into more
than two components, and directing said components toward said area
to identify the extent of said radiation zone.
32. A method of visibly outlining an energy zone on a surface whose
temperature is to be measured using a radiometer, said method
comprising the steps of: providing a sighting device for use in
conjunction with said radiometer, said device including means for
generating a laser beam; splitting said laser beam into more than
two split laser lines; and directing said laser lines towards said
surface to outline visibly the periphery of said entire energy
zone.
33. A method for identifying an energy zone whose temperature is to
be measured using a radiometer, said method comprising the steps
of: providing a sighting device for use in conjunction with said
radiometer, said device including means for generating laser beams;
splitting said laser beams into split laser lines; directing said
laser lines towards said zone; and positioning said laser lines to
identify the periphery of said entire zone.
34. A method for visibly outlining an energy zone on a surface
whose temperature is to be measured using a radiometer, said method
comprising the steps of: providing a sighting device means for use
in conjunction with said radiometer, said device including means
for generating a laser beam; splitting said laser beam into more
than two split laser lines; directing said laser lines toward said
surface, and positioning said laser lines to outline visibly the
periphery of said zone.
35. The method of claim 34, wherein said split laser lines identify
the extent of said energy zone.
36. Apparatus for use in conjunction with a radiometer for
identifying a radiation zone in an area whose temperature is to be
measured using said radiometer, said apparatus comprising a laser
sighting device for use in conjunction with said radiometer, said
laser sighting device including: means for generating a laser beam;
means for splitting said laser beam into more than two components;
and means for positioning said components to identify the extent of
said entire radiation zone.
37. Apparatus for use in conjunction with a radiometer for visibly
outlining an energy zone on a surface whose temperature is to be
measured using said radiometer, said apparatus comprising a laser
sighting device for use in conjunction with said radiometer, said
laser sighting device including: means for generating a laser beam;
means for splitting said laser beam into more than two split laser
lines; and means for directing said laser lines towards said
surface; and means for positioning said laser lines to outline
visibly the periphery of said energy zone.
38. Apparatus for use in conjunction with a radiometer for
identifying the extent of an energy zone whose temperature is to be
measured using said radiometer, said apparatus comprising a laser
sighting device co-operating with said radiometer for emitting more
than two laser beams toward said energy zone along separate paths;
and means for adjusting said paths of said laser beams to outline
the periphery of said zone.
39. Apparatus for measuring the intensity of detected radiation
comprising: a radiation detector having means for measuring the
intensity of said detected radiation; a laser sighting device for
directing more than two laser beams along axes in the direction of
the radiation to be detected to define the limits of the zone of
radiation to be measured; and means for integrating the detected
radiation intensity measurement and the zone of radiation as
defined by the laser beams.
40. A method for identifying an energy zone whose temperature is to
be measured using a radiometer, said method comprising the steps
of: providing a laser sighting device; causing said sighting device
to emit more than two laser beams toward said surface along
separate paths; adjusting said paths of said laser beams to outline
visibly the periphery of said energy zone.
41. Apparatus for identifying an energy zone whose temperature is
to be measured using a radiometer, said apparatus including: a
laser sighting device for emitting more than two laser beams toward
said surface; and means for adjusting said laser beams to outline
visibly the periphery of said energy zone.
42. In apparatus for temperature measurement comprising: a) a
detector responsive to infrared radiation from an energy zone on a
surface to be measured, b) an optical system directing said
radiation from said energy zone onto said detector, c) and a
sighting device for ascertaining the position and size of the
energy zone on said surface to by measured, by visible laser light,
the improvement in which: d) the sighting device includes a beam
splitter element for production of more than two laser beams
outlining visibly the periphery of substantially said entire zone
and for spreading the laser light intensity.
43. In a laser sighting device for visibly outlining an energy zone
to by measured by a radiometer when measuring the temperature of a
surface, including means projecting more than two laser beams
toward said surface, the improvement comprising means causing said
laser beams to strike the periphery of said zone and visibly
outlining said entire zone.
44. A device according to claim 43 including means projecting at
least one laser beam to identify the center of said zone.
45. A temperature measurement device comprising a detector for
receiving heat radiation from a measuring zone of the object under
examination, and a direction finder sighting device including a
laser generator providing a laser beam serving as a light source,
said sighting device further including a holographic beam splitter
providing subdivisional laser beams to strike the object and show
thereon at least three illuminated areas at the periphery of and
enclosing and defining the measuring zone.
46. A method for visibly outlining an energy zone on a surface
where temperature is to be measured using a radiometer, said method
comprising the steps of: providing a laser sighting device with
said radiometer and a laser beam splitting device; emitting more
than two laser beams from said device striking against said surface
about the periphery of about 90% of said energy zone; projecting,
from said laser beam splitting device, more than two spots at the
circumference of said zone positioned so as to encompass, configure
and outline said circumference and so visibly outlining said
zone.
47. Apparatus for use in conjunction with a radiometer for visibly
outlining an energy zone on a surface where temperature is to be
measured using said radiometer, said apparatus comprising: a laser
sighting device co-operating with said radiometer, for emitting
more than two laser beams against said surface; and means
positioning said laser beams about said energy zone to outline
visibly the periphery of said zone.
48. The apparatus of claim 47, wherein said means for positioning
said laser beams comprises a splitter which is adapted to split
said laser beams into a plurality of beams which are then directed
against said surface to define the energy zone.
Description
RELATED APPLICATIONS
[0001] This is a continuation-in-part application of both pending
U.S. patent applications Ser. Nos. 08/764,659 filed on 11 Dec. 1996
and 08/617,265 filed on 18 Mar. 1996 in the names of Milton B.
Hollander and W. Earl McKinley for Method and Apparatus for
measuring Temperature Using Infrared Techniques, the latter of
which, is a continuation-in-part application of U.S. application
Ser. No. 08/348,978 filed on 28 Nov. 1994, now U.S. Pat. No.
5,524,984 which in turn was a continuation-in-part application of
then copending U.S. patent application Ser. No. 08/121,916 filed 17
Sep. 1993, now issued as U.S. Pat. No. 5,368,392, on 29 Nov.
1994.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to a method and
apparatus for more accurately measuring the temperature of a
surface using infrared measurement techniques and, more
particularly, to such a method and apparatus which utilizes a laser
sighting device which is adapted to project at least a
circumscribing laser sighting beam or beams for more clearly
defining the periphery of the energy zone from which the
temperature is measured. Generally speaking, this has been
accomplished by directing the laser beam about the periphery of the
energy zone; by the use of three or more stationary laser beams
which are focused on the periphery of the energy zone; or by the
use of a controlled single laser beam directed towards three or
more predetermined locations on the periphery of the energy zone.
In the alternative embodiment, a single laser beam may be rotated
around the periphery of the energy zone using, for example, slip
rings. In another embodiment, the single rotating laser may be
pulsed on and off in a synchronized manner in order to produce a
series of intermittent lines outlining the energy zone, thus
increasing the efficiency of the laser by concentrating its total
wattage in a smaller area, causing a brighter beam. Further, the
circumscribing beam or beams may be used in conjunction with an
additional beam directed at and defining a central spot, or larger
central area, of the energy zone.
[0004] In yet another method and embodiment, at least one laser
beam is subdivided by passing it through a diffraction grating, for
example, into a plurality of three or more subdivision beams which
can form a pattern of illuminated spot areas on a target whose
energy zone is to be investigated with a radiometer. Herein "a
plurality" means three or more, e.g. six or twelve.
DESCRIPTION OF THE PRIOR ART
[0005] Remote infrared temperature measuring devices (commonly
referred to as infrared pyrometers or radiometers) have been used
for many years to measure the temperature of a surface from a
remote location. Their principle of operation is well known. All
surfaces at a temperature above absolute zero emit heat in the form
of radiated energy. This radiated energy is created by molecular
motion which produces electromagnetic waves. Thus, some of the
energy in the material is radiated in straight lines away from the
surface of the material. Many infrared radiometers use optical
reflection and/or refraction principles to capture the radiated
energy from a given surface. The infrared radiation is focused upon
a detector, analyzed and, using well known techniques, the surface
energy is collected, processed and the temperature is calculated
and displayed on an appropriate display.
[0006] Examples of such infrared radiometers are illustrated at
pages J-1 through J-42 of the Omega Engineering Handbook, Volume
2B. See, also, U.S. Pat. No. 4,417,822 which issued to Alexander
Stein et al. on Nov. 29, 2983 for a Laser Radiometer; U.S. Pat. No.
4,527,896 which issued to Keikhosrow Irani et al. on Jul. 9, 1985
for an Infrared Transducer-Transmitter for Non-Contact Temperature
Measurement; and U.S. Pat. No. 5,169,235 which issued to Hitoshi
Tominaga et al. for Radiation Type Thermometer on Dec. 8, 1992.
Also see Baker, Ryder and Baker, Volume II, Temperature Measurement
in Engineering, Omega Press, 1975, Chapters 4 and 5.
[0007] When using such radiometers to measure surface temperature,
the instrument is aimed at a target or "spot" within the energy
zone on the surface on which the measurement is to be taken. The
radiometer receives the emitted radiation through the optical
system and is focused upon an infrared sensitive detector which
generates a signal which is internally processed and converted into
a temperature reading which is displayed.
[0008] The precise location of the energy zone on the surface as
well as its size are extremely important to insure accuracy and
reliability of the resultant measurement. It will be readily
appreciated that the field of view of the optical systems of such
radiometers is such that the diameter of the energy zone increases
directly with the distance to the target. The typical energy zone
of such radiometers is defined as where 90% of the energy focused
upon the detector is found. Heretofore, there have been no means of
accurately determining the perimeter of the actual energy zone
unless it is approximated by the use of a "distance to target
table" or by actual physical measurement.
[0009] Target size and distance are critical to the accuracy of
most infrared thermometers. Every infrared instrument has a field
of view (FOV), an angle of view in which it will average all the
temperatures which it sees. Field of view is described either by
its angle or by a distance to size ratio (D:S). If the D:S=20:1,
and if the distance to the object divided by the diameter of the
object is exactly 20, then the object exactly fills the
instrument's field of view. A D:S ratio of 60:1 equals a field of
view of 1 degree.
[0010] Since most infrared thermometers have fixed-focus optics,
the minimum measurement spot occurs at the specified focal
distance. Typically, if an instrument has fixed-focus optics with a
120:1 D:S ratio and a focal length of 60" the minimum spot
(resolution) the instrument can achieve is 60 divided by 120, or
0.5" at a distance of 60" from the instrument. This is significant
when the size of the object is close to the minimum spot the
instrument can measure.
[0011] Most general-purpose infrared thermometers use a focal
distance of between 20" and 60" (50 and 150 cm); special
close-focus instruments use a 0.5" to 12" focal distance. See page
Z54 and Z55, volume 28, The Omega Engineering Handbook, Vol. 28. In
order to render such devices more accurate, laser beam sighting
devices have been used to target the precise center of the energy
zone. See, for example, pages C1-10 through C1-12 of The Omega
Temperature Handbook, Vol. 27. Various sighting devices such as
scopes with cross hairs have also been used to identify the center
of the energy zone to be measured. See, for example, Pages C1-10
through C1-21 of The Omega Temperature Handbook, Vol. 27.
[0012] The use of a laser to pinpoint only the center of the energy
zone does not, however, provide the user with an accurate
definition of the actual energy zone from which the measurement is
being taken. This inability frequently results in inaccurate
readings. For example, in cases where the area from which radiation
emits is smaller than the target diameter limitation (too far from
or too small a target), inaccurate readings will occur.
[0013] One method used to determine the distance to the target is
to employ an infrared distance detector or a Doppler effect
distance detector or a split image detector similar to that used in
photography. However, the exact size of the energy zone must still
be known if one is to have any degree of certainty as to the actual
area of the surface being measured. This is particularly true if
the energy zone is too small or the surface which the energy zone
encompasses is irregular in shape. In the case where the surface
does not fill the entire energy zone area, the readings will be low
and, thus, in error.
[0014] Similarly, if the surface is irregularly shaped, the
readings will also be in error since part of the object would be
missing from the actual energy zone being measured.
[0015] Thus, the use of a single laser beam only to the apparent
center, of the energy zone does not insure complete accuracy since
the user of the radiometer does not know specifically the
boundaries of the energy zone being measured.
[0016] As will be appreciated, none of the prior art recognizes
this inherent problem o offers a solution to the problems created
thereby.
[0017] Proposals have ben made in the prior art for indicating an
energy zone area of a target surface by means visible to the eye of
the target.
[0018] A first kind of such indication utilizes multi-spectral
light, as evidenced for example in the Japanese Publication No.
S57-22521 which teaches the use of an incandescent light source to
outline an energy zone at the target. Japanese Publication No.
62-12848 suggests a similar use of multi-spectral light to outline
an energy zone at the target. Reference is made to Japanese case JP
63-145928.
[0019] Further, U.S. Pat. No. 4,494,881 EVEREST also suggests using
a multi-spectral light source together with a beam splitter
arrangement which permits the infra-red received beam and the
multi-spectral light to utilize the same optical arrangement.
EVEREST teaches the use of a visible light source such as an
incandescent lamp or strobe light which is projected against the
target surface, the temperature of which is to be measured. This
adds additional energy to the same energy zone where the
temperature measurement is to be taken, and this destroys accuracy.
When EVEREST uses a beam splitter, the incandescent light beam
causes the beam splitter to act as a radiator of infrared energy.
When EVEREST uses a Fresnel lens, the light tends to elevate the
temperature of the Fresnel lens, which in turn reflects back to the
infra-red detector.
[0020] This manner of indication, utilizing incoherent
multi-spectral light, has the disadvantage amongst others that the
multi-spectral light itself has a heat factor which can cause
incorrect reading by the energy detecting means of the
apparatus.
[0021] A laser is Light Amplification by Stimulated Emission of
Radiation. This device was invented in 1960 to produce an intense
light beam with a high degree of coherence. Atoms in the material
emit in phase. Laser light is used in holography. A light beam is
coherent when all component waves have the same phase. A laser
emits coherent light, but ordinary electric incandescent light is
incoherent in which atoms vibrate independently.
[0022] It is not possible simply to substitute a laser for an
incandescent light source, because the incandescent beam is
incoherent in nature, so that when projected parallel and in close
proximity to the boundaries of the invisible infra-red zone,
incandescent light inside the infra-red zone is reflected as heat
energy. Moving the incandescent beam well away from the infra-red
zone clearly does not permit accurate delineation of the target
zone.
[0023] A second kind of energy zone indicator utilizes coherent
laser light, as evidenced for example in U.S. Pat. No. 4,315,150 of
DERRINGER, which is directed to a targeted infrared thermometer in
which a laser is provided to identify the focal point, i.e., the
center, of the energy zone, but there is nothing in DERRINGER to
suggest causing more than two laser beams to outline the energy
zone.
[0024] U.S. Pat. No. 5,085,525 BARTOSIAK ET AL teaches use of a
laser beam to provide a continuous or interrupted line across a
target zone to be investigated, but there is no suggestion to
outline a target zone, nor to indicate a central point or central
area of the target zone.
[0025] German patent publications of interest include:
[0026] DE-38 03 464
[0027] DE-36 07 679 to a laser sighting device.
[0028] DE-32 13 955 to a beam splitter and to dual laser beams to
indicate position and diameter of the energy zone
[0029] All of the above noted prior art is hereby incorporated into
this case by reference thereto.
SUMMARY OF THE INVENTION
[0030] Against the foregoing background, it is a primary object of
the present invention to provide a method and apparatus for
measuring the temperature of a surface using infrared
techniques.
[0031] It is another object of the present invention to provide
such a method and apparatus which provides more accurate
measurement of the surface temperature than provided by the use of
techniques heretofore employed.
[0032] It is yet another object of the present invention to provide
such a method and apparatus which permits the user visually to
identify the location, size nd temperature of the energy zone on
the surface to be measured.
[0033] It is still yet another object of the present invention to
provide such method and apparatus which employs a heat detector and
a laser beam or beams for clearly outlining the periphery of the
energy zone of the surface.
[0034] It is a still further object of the present invention to
provide a method and apparatus which permits the use of a single
laser beam which is subdivided by passing it through, or over, a
beam splitter, holographic element or a diffraction grating,
thereby to form a plurality of three or more subdivision beams
which provide a pattern where they strike a target whose energy
zone is to be investigated.
[0035] It is still further object of the invention to provide a
method and apparatus which utilizes not only a beam or beams for
outlining the energy zone, but also an additional beam or beams
directed at and illuminating an axial central spot, or larger
central area, of the energy zone.
[0036] For the accomplishment of the foregoing objects and
advantages, the present invention, in brief summary, comprises a
method and apparatus for visibly outlining the energy zone to be
measured by a radiometer. The method comprises the steps of
providing a radiometer with a detector and a laser sighting device
adapted to emit at least one laser beam against a surface whose
temperature is to be measured and controlling said laser beam
towards and about the energy zone to outline visibly said energy
zone. The beam is controlled in such a fashion that it is directed
to three or more predetermined points of the target zone. This can
be done mechanically or electrically.
[0037] Another embodiment of this invention employs a plurality of
three or more laser beams to describe the outline and optionally
also the center of the energy zone either by splitting the laser
beam into a number of points through the use of optical fibres or
beam splitters or a diffraction device or the use of a plurality of
lasers. One embodiment of the apparatus comprises a laser sighting
device adapted to emit at least one laser beam against the surface
and means to rotate said laser beam about the energy zone to
outline visibly said energy zone. This rotation can be by steps or
continuous motion.
[0038] Another embodiment consists of two or more stationary beams
directed to define the energy zone. The three or more laser beams
could each be derived from a dedicated laser to each beam or by
means of beam splitters. This can be accomplished by mirrors,
optics, a diffraction grating, and fibre optics.
[0039] Another embodiment consists of a laser beam splitting device
that emits one laser beam which is split into a plurality of three
or more beams, by a diffraction grating, for example, to outline
the energy zone and optionally to indicate a central spot or larger
central area of the energy zone.
[0040] In a still further embodiment, the temperature measurement
device comprises a detector for receiving the heat radiation from a
measuring point or zone of the object under examination. Integral
to the equipment is a direction finder, i.e. a sighting device
using a laser beam as the light source and incorporating a
diffractive optic, i.e. a holographic component such as a
diffraction grating, or a beam splitter, with which the light
intensity distribution is also shown and the position and size of
the heat source is indicated. The marker system relates to a
predetermined percentage, e.g. 90%, of the energy of the radiated
heat.
[0041] The method includes visually outlining and identifying the
perimeter of the energy zone by projecting more than two laser
beams to the edge of the 90% energy zone to mark out the limits of
the surface area under investigation, for example, by a series of
dots or spots which form a pattern.
[0042] Two or more embodiments may be used together or
alternately.
BRIEF DESCRIPTION OF THE DRAWINGS
[0043] The foregoing and still other objects and advantages of the
present invention will be more apparent from the detailed
explanation of the preferred embodiments of the invention in
connection with the accompanying drawings, wherein:
[0044] FIG. 1 is a schematic illustration of the prior art type of
radiometers using laser sighting devices;
[0045] FIG. 2 is a schematic illustration of one embodiment of the
present invention in which the laser beam is circumscribing the
target zone using a mirror;
[0046] FIGS. 2A and 2B illustrate the manner in which the laser
beam is relocated in stepped fashion to identify the energy
zone;
[0047] FIG. 3 is schematic illustration of an alternative
embodiment of the present invention in which the laser is pivoted
about a pivot point by the use of mechanical motive means;
[0048] FIG. 4 is a schematic illustration of another alternative
embodiment of the present invention in which the laser is directed
through a magnetic field to identify the target zone;
[0049] FIG. 5 is a schematic illustration of another alternative
embodiment of the present invention in which a number of individual
laser beams are projected so as to define the energy zone being
measured;
[0050] FIG. 6 is a schematic illustration of another alternative
embodiment of the present invention in which the laser is
mechanically pivoted;
[0051] FIG. 7 schematically illustrates the positioning of fiber
optics to create a pattern of the target zone with the laser
beam;
[0052] FIG. 8 is a detailed sectional view of another alternative
embodiment of the present invention in which the laser is
mechanically pivoted about the detector;
[0053] FIGS. 9A-C illustrate alternative configurations of the
outlines which can be projected using the apparatus of the present
invention;
[0054] FIG. 10 is a schematic illustration of an embodiment of the
invention wherein the laser is divided into a plurality of laser
beams defining the energy zone by the use of optical fibres.
[0055] FIG. 11 is a cross sectional side view of a laser sighting
device which may be used in conjunction with a radiometer in which
the laser is rotated using slip rings;
[0056] FIG. 12 is a side view illustrating a modified version of
the laser sighting device of FIG. 11 with the sighting device
mounted on an infrared detector;
[0057] FIG. 13 is a side view illustrating still another modified
version of the laser sighting device of the present invention;
[0058] FIG. 14 is a side view of yet another embodiment of the
invention in which the laser sighting device utilizes twin laser
beams provided on opposite sides of an infrared detector;
[0059] FIG. 15 is a front view of the embodiment of FIG. 14;
[0060] FIG. 16 is a top view of the embodiment of FIGS. 14-15;
[0061] FIG. 17 illustrates the intermittent lines formed by a laser
which is pulsed on and off in a synchronized manner;
[0062] FIG. 18 is an illustration in partial section of a preferred
embodiment of the invention in which the laser sighting device
utilizes a single laser beam which is divided and spread into a
plurality of individual beams by means of a diffraction
grating;
[0063] FIG. 19 is a diagram to show a pattern of dots of laser
light, formed on a target area, as a result of impingement of the
individual beams resulting from sub-division of the single beam of
the laser;
[0064] FIG. 20 is a diagram to show a modification wherein the
radiometer is arranged on the axis of the laser beam.
BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0065] Traditionally, prior art radiometers have long employed
laser sighting devices and direction finders to assist in the
proper aim and alignment of the instrument. FIG. 1 illustrates and
direction finders the operation of traditional, prior art, hand
held radiometers. Such a radiometer, referred to generally by
reference numeral 10, includes a laser sight scope 12 which emits a
laser beam 14 to a spot or target 18 on the surface 20 whose
temperature is to be measured. This spot 18 is located in the
center of the energy zone "E" which is to be measured by the
radiometer 10. The radiometer 10 includes a detector 16 which is
connected to conventional internal circuitry and display means (not
shown) for conversion, calculation and display of the temperature
of the surface 20 calculated indirectly from the energy radiated
from the surface within the energy zone E. Such energy is radiated
in straight lines in all directions away from the surface 20 and
captured with the detector 16 on the radiometer 10. Using infrared
radiation principles, the radiometer is thus able to capture and
measure the infrared energy in the energy zone E and to display the
surface temperature thereof.
[0066] The actual size and shape of the energy zone E is determined
by the optics of the radiometer and the distance between the
radiometer and the target. Each radiometer has a defined angle of
vision or "Field of view" which is typically identified in the
instrument's specification sheet. The size of the energy zone E is
predetermined when the field of view is known in conjunction with
the distance to the target. Obviously, the further the radiometer
is held from the target (i.e., the greater the distance), the
larger the energy zone E.
[0067] This can be expressed in a "distance to spot size zone". For
example, with a "distance to spot size zone" of 40:1 the periphery
of the energy zone would have a 1" diameter at a distance of 40"
or, at a distance of 20" the diameter of the energy zone would be
1/2". The manufacturer of the pyrometer usually provides field of
view diagrams for determining the energy zone at specific
distances.
[0068] As can readily be appreciated, however, such laser aiming
devices are merely able to identify the center of the energy zone
being measured and not the outer periphery, as distinct from the
diameter, of the actual energy zone from which the measurement is
being taken. The further away from the surface the radiometer 10 is
positioned, the larger the energy zone E. Thus, depending upon the
size and configuration of the surface 20, the actual energy zone E
may, conceivably, include irregular shaped portions of the surface
20 or even extend beyond the edges of the surface. Of course, in
such instances, the resultant measured temperature would be
inaccurate. Without knowing the outer perimeter of such energy zone
E, the user of the radiometer 10 would have no knowledge of such
fact and the resultant readings could be inaccurate.
[0069] The present invention provides a means for visibility
defining the energy zone E so that the user of the radiometer 10
can observe the actual energy zone being measured to determine
where it falls relative to the surface being measured. In the
various embodiments of this invention, a fine laser line or lines
is projected against the surface being measured and such line or
lines is positioned so as to encompass the periphery of the energy
zone E. Of a rotating laser beam is employed, positioning can be
effected, alternatively by moving either the laser itself or the
laser beam emitted from the laser or from a laser beam
splitter.
[0070] If the perimeter of the energy zone E cold be identified on
the object by the movement of the laser beam in a path about the
circumference of the energy zone E, the user would be able quickly
and accurately to determine if the energy zone from which the
measurement was being taken was fully on the surface to be measured
and whether its surface was of the type which would provide an
otherwise accurate measurement.
[0071] The periphery of the energy zone E is identified as a
function of the stated "field of view" of the particular radiometer
as identified in its specifications and the distance between the
radiometer and the target. Identification of the size and shape of
the energy zone is easily done using conventional mathematical
formulae. Once identified, the laser beams are then projected about
the periphery of the energy zone E in accordance with the methods
and apparatus hereinafter described. One simple "aiming" approach
is to project the laser beam at the same angle as the field of view
of the radiometer emanating from the same axis or, alternatively,
by mechanically adjusting the laser beam angle in accordance with
the "distance to spot size ratio" calculations. In either event,
the periphery of the energy zone E would be identified by the laser
beams.
[0072] FIG. 2 illustrates a first embodiment of the present
invention in which the laser aiming device 12 emits a laser beam 14
which is aimed at a mirrored surface 30 which is positioned in
front of the laser beam 14. The mirror 30 is rotated using motive
means 32 so as to rotate the beam in a circular fashion to define
the energy zone E on the surface being measured. Alternatively, the
mirror 30 can be rotated by vibratory means or by the application
of a magnetic field (not shown). Rotation of the mirror 30 should
be a refraction angle which corresponds to the 90% energy zone E
thereby permitting the laser beam 14 to rotate about the periphery
of the energy zone E and thereby making it visible to the user of
the radiometer 10.
[0073] It should be appreciated that the laser aiming device 12 may
be an integral part of the radiometer 10 or, alternatively, a
separate unit that may be mounted on or near the radiometer 10.
[0074] Alternatively, a prism can be used in place of the mirror 30
with predetermined angles to cause the prism to function as the
reflecting mirror surface and, thereby, direct the laser beam about
the perimeter of the energy zone.
[0075] FIGS. 2A and 2B illustrate the manner in which laser beams
can be used to outline the energy zone E on the surface to be
measured. It is important that rotation of the beam 14 be carefully
controlled so that rotation is at a speed which can be visually
followed. This will permit full beam intensity. As illustrated in
FIGS. 2A and 2B, the laser beam is rotated about the energy zone E
through a series of steps with the laser beam being permitted to
remain in each step for at least one hundredth of a second before
moving to its next position. This is accomplished by creating a
plurality of steps E-1, E-2, etc., around the energy zone E. The
laser beam 114 would stop at each step for the predetermined period
of time to permit the beam to be observed before moving to the next
step.
[0076] FIG. 3 illustrates another embodiment of the present
invention in which the laser 112 itself is rotated or displaced so
as to scribe a circle or other closed figure which defines the
energy zone E by mechanically pivoting the laser 112 about pivot
point 120 using motive means 132. Alternatively, the laser 112 can
be rotated by a vibratory means (not shown) or by the application
of a magnetic field (not shown). Rotation of the laser 112 should,
however, be at a refraction angle which corresponds to the 90%
energy zone E thereby permitting the laser beam 114 to rotate about
the periphery of the energy zone E to make it visible to the user
of the radiometer 10.
[0077] In FIG. 4, the laser 212 is rotated about a pivot point 220
by the application of a magnetic field 225 so as cause the emission
of the laser beam 214 around the periphery of the 90% energy zone E
to make the beam visible to the user of the radiometer 10. In such
embodiment, means (not shown) are provided for modifying the
magnetic field 225 to correspond to the 90% energy zone so as to
permit the laser to be rotated accordingly.
[0078] In FIG. 5, the laser 312 has at least two components 312A
and 312B which produce at least two individual laser beams 314A and
314B about the detector 316. These at lest two individual beams
314A and 314B are directed to the surface 320 being measured at the
perimeter of the energy zone E rather than at the center of the
energy zone E. Through the use of a number greater than two of such
laser beams, the significant energy zone E becomes clearly
identified rather than merely the center of the E zone. If desired
individual lasers can be used or laser splitting devices can be
used to split a single laser beam. A diffraction device such as a
grating or holographic component may be used to form multiple
beams. Two lasers may be adapted to project a pair of laser beams
on different sides of said energy zone.
[0079] FIG. 6 illustrates yet another embodiment of the present
invention in which the laser 412 is mechanically pivoted in a
circular fashion around the detector 416 so as to emit a laser beam
414 in a circular path on the surface (not shown) thereby defining
the energy zone E. Laser 412 is pivotally mounted on pivot bearing
420 provided on connecting arm 421. Arm 421 is mounted on pivot
bearing 424 which is rotated by motor 422. In such a manner, the
laser beam 414 emitted from the laser 412 rotates about and
outlines the energy zone E on the surface from which the
temperature is being measured.
[0080] The rotation of the laser beam may be effected using beam
splitter or fiber optic techniques as shown in FIG. 7 in which the
laser beam is projected through fiber optic means 501. In such
manner, the beams fan out from the laser source and encircle and
thereby define the energy zone E. By the use of a sufficient number
of fiber optics, one can outline the circumference of the target
area E with a light ring or by a ring of dots. This can be
accomplished by as few as two fibers 501 positioned 180 degrees
apart since the pick up pattern would be circular. Further fiber
optic means may serve to direct a laser beam onto a central spot,
or larger central area, of the energy zone.
[0081] FIG. 8 illustrates still another means of effecting rotation
of the laser beam 614 emitted from laser 612. In this manner, the
laser beam 614 is directed against a rotating flat surface mirror
630 where it is reflected against a plated plastic cone mirror 631.
The reflected beam is then projected to the surface and defines the
perimeter of the energy zone E. The flat mirror 630 is driven by
motor 622. In such manner, the laser beam 614 rotates about the
circumference of the energy zone E on the surface being measured.
The mirrors are positioned at such an angle that the laser
projection is at the same angle as the infrared detector pickup
angle.
[0082] It will, of course, be appreciated that the energy zones E
may assume configurations other than the circular configuration
shown in FIGS. 1-8. FIGS. 9A-C illustrate alternative square (FIG.
9A), rectangular (FIG. 9B), and triangular (FIG. 9C) configurations
for the light patterns which may be accomplished using the means of
the present invention. A closed configuration is preferred. This
may include three or more dots or spots.
[0083] FIG. 10 illustrates a method for defining the energy zone
where a circular configuration can be accomplished without rotation
of the laser beam wherein a plurality of fixed optical fibers
positioned to project a number of spots is employed. In this
figure, a fixed laser 712 projects a beam 713 which is split into a
plurality of beams 714 by a bundle of optical fibers 715 in order
to project a pattern 716 onto the surface defining the energy zone
E. Additional configurations may also be used, if desired. A
diffraction means will also produce a pattern.
[0084] Referring to FIG. 10, the means for projecting a plurality
of laser beams (the bundle 715) will likewise include optical
fibers arranged to project a laser beam axially so as to cause the
plurality of laser beams to identify and define both the center and
the periphery of the energy zone, e.g. by providing a single center
spot or larger central area on the surface to be measured.
[0085] FIGS. 11-12 illustrate further embodiments of the present
invention in which the laser is adapted to be rotated by the use of
slip rings and counter weights. For example, FIG. 11 illustrates
one laser sighting device 1000. Laser sighting device 1000 can be
provided as an integral unit in combination with an infrared
detector (not shown) or, alternatively, may be self contained as a
removable sighting device which can be attached to and removed from
infrared detectors.
[0086] The laser sighting device 1000 of FIG. 11 includes a laser
1012 powered by power source 1018 which projects a laser beam 1014
against target. The laser 1012 is pivotally mounted about pivot
1020. Motor 1021 is provided for powering the sighting device and
causing the laser 1012 to rotate. An external switch (not shown)
may be provided to turn the motor 1021 on and off and, as such, the
rotation of the laser 1012. Upper and lower screw adjustments of
1013 and 1011, respectively, are provided for controlling the
position of the laser 1012 and, more importantly, the direction of
the laser beam 1014. Upper screw adjustment 1013 is adapted to be
used during non-rotation while lower screw adjustment 1011 issued
during rotation of the laser 1012.
[0087] The laser 1012 is powered with power source 1018. Slip rings
1016 are provided to facilitate rotation of the laser 1012. Upper
and lower counterweights 1015A and 1015B, respectively are provided
above and below the laser 1012 and a return spring 1019 is also
provided.
[0088] The laser 1012 of the sighting device 1000 in FIG. 11 is
adapted to rotate about the pivot 1020 when driven by the motor
1021. Thus, the laser 1012 is able to project a laser beam 1014
with a circle-type pattern against a target (not shown). During
rotation, centrifugal force will act upon the counterweights 1015A
and 1015B causing the laser 1012 to tilt. The angle at which it
tilts can be controlled by the screw adjustment 1013 and 1011. The
angle is adjusted to correspond to the infrared detector field of
the infrared detector in which the sighting device is used. The
laser beam 1014 will then follow the periphery of the target zone
of the infrared detector (not shown). Once the motor 1021 is turned
off, the return spring 1019 will cause the laser 1012 to center. In
this manner, the laser beam will now be in the center of the target
zone. This serves as a calibration for the user and insures that
the laser sighting device is properly aimed.
[0089] A modified version of the laser sighting device of FIG. 11
is illustrated in FIG. 12. Laser sighting device 1100 is shown in
combination with an infrared detector 1162 which has an infrared
field of view 1161. Laser sighting device 1100 includes a laser
1112 which projects a laser beam 1114. Laser 1112 is pivotally
mounted on pivot 1120. A counterbalance 1115 is provided on the
side of the laser 1112 opposite the pivot 1115. The laser 1112 is
powered by power source 1118 and adapted to be rotated by motor
1121. Slip rings 1116 are provided for facilitating the rotation of
the laser 1112.
[0090] The laser sighting device 1100 of FIG. 12 is adapted to
operate in the same way as sighting device 1000 of FIG. 11. As the
laser 1112 is rotated about the pivot point 1120, the laser beam
1114 is projected against the target (not shown) about the
periphery of the infrared field of view 1161 of the infrared
detector 1162.
[0091] FIG. 13 illustrates yet another embodiment of the laser
sighting device of the present invention. Laser sighting device
1200 is provided as a stand-alone unit which may be mounted on and
removed from standard infrared detectors or radiometers. The
sighting device 1200 includes a laser 1212 container within the
housing 1201 of the sighting device 1200. Laser 1212 is adapted to
project a laser beam 1214 against a target (not shown). The laser
1212 is powered by a power source (not shown). A motor 1221 is
connected to the laser 1212 by rotational assembly 1227 thereby
causing the laser to rotate within the housing 1201. A slider 1226
is further provided to facilitate rotation of the laser 1212 within
the housing.
[0092] Adjustment screw 1217 is further provided for controlling
the position of the motor 1221 and, as such, the direction of the
laser beam 1214. A swivel ball 1222 is provided about the outward
end of the laser 1212 which is seated in swivel ball seat 1220.
Spring washer 1218 is further provided adjacent the swivel ball
1222.
[0093] The laser sighting device 1200 operates in substantially the
same manner as the sighting devices depicted in FIGS. 11-12 in that
he single laser 1212 is rotated by motor 1221 to cause the
projecting laser beam to circle around the periphery of an infrared
field.
[0094] FIGS. 14-16 illustrate yet another version of the laser
sighting device of the present invention shown in combination with
a radiometer. In the embodiment of FIGS. 14-16, a conventional
radiometer 1300 is provided. The radiometer includes a telescope
aiming sight 1305 with a lens 1306 mounted on the top thereof.
Telescope aiming sight 1305 permits the user to aim the radiometer
1300 against a target.
[0095] At least two laser sighting devices 1312 are provided on
opposite sides of the radiometer 1300. Device 1312 includes a pair
of lasers 1314 provided within the laser sighting devices 1312
positioned on each side of the radiometer approximately 180 degrees
apart which are adapted to project a pair of laser beams (not
shown) toward a target on either side of the energy zone to be
measured by the radiometer. In this manner, the laser beams are
used to define the outer periphery of the energy zone being
measured by the radiometer 1300.
[0096] In an alternate embodiment, the lasers depicted in FIGS.
11-16 may be pulsed on and off in a synchronized manner. FIG. 17
depicts the series of intermittent lines that serve to outline the
energy zone in such an embodiment. The intermittent use of the
laser in this embodiment results in an increase in the efficiency
of the laser, which, in turn, allows for an increased concentration
of the laser's total wattage in a smaller area, causing a brighter
beam.
[0097] FIGS. 18 and 19 illustrate yet another and preferred best
mode version of the laser sighting device of the present invention,
in combination with a radiometer. In this embodiment, a
conventional radiometer 1400 is provided. A laser sighting device
denoted generally by reference numeral 1401 has a single-beam laser
generator 1402 which produces the laser beam 1403. Aligned axially
with the laser beam 1403, and in front of the laser generator 1402,
there is positioned a support 1404 housing a beam splitter,
holographic component or a diffraction grating 1405. In this
instance, the diffraction grating 1405 is selected when struck by
the laser beam to produce, from the entering single beam 1403, a
total of twelve sub-division beams 1403a which are symmetrically
divergent about the axis 1406. Referring to FIG. 19 there is shown
the pattern of laser light spots 1403b which are formed at
individual mutually spaced locations, where the sub-division beams
1403a strike the target 1407 whose temperature is to be
investigated. Due to the nature of the diffraction grating 1405,
the spots 1403b are circumferentially equidistantly spaced by
distance B in a circle about the axis of the laser beam 1403, and
the total spread of the sub-division beams 1403a is a width A which
depends upon the axial distance of the device from the target 1407.
Adjacent to and laterally of the laser generator 1402 in its
support 1404 there is positioned a radiometer 1400 whose viewing
axis is parallel to the axis 1406 of the generated laser beam, but
which may if desired be made adjustable with respect to the axis
1406 so that a selected area of the target, perhaps not at the
center of the dots 1403b, may be investigated.
[0098] The apparatus of any one of FIGS. 2, 3, 4, 6, 8, 11, 12, 13
and 18 may further include means for projecting a laser beam
axially to strike the surface zone to be measured, e.g. in FIG. 18
the diffraction grating 1405 would be selected to provide not only
the sub-division beams 1403a, but also a central sub-division beam
along the axis 1406.
[0099] Referring to FIG. 20, there is shown schematically a
modification wherein the radiometer 1400 is situated on the central
longitudinal axis of the laser generator 1401 and within said
plurality of laser beams at a suitable distance downstream of the
diffraction grating so as not to interference with the transmission
of the sub-division beams to form the pattern of spots.
[0100] In a practical form of construction, the laser beam
generator 1401 and the diffraction grating support 1404 and the
radiometer would conveniently be carried on a support structure,
not shown, to provide a hand-held apparatus aimed at a selected
area, or areas, to be investigated. Thus a method of identifying
the extent of a radiation zone on a region whose temperature is to
be measured may comprise the steps of providing a sighting device
for use in conjunction with said radiometer, said device including
means for generating a laser beam, splitting said laser beam into a
plurality of three or more components by passing said beam through
or over diffraction grating means, and directing said beam
components towards said region so as to form a plurality of
illuminated areas on said region where said beam components impinge
on said region, and determining temperature at said region with
said radiometer. Preferably, the diffraction grating means is such
as to cause the laser beam to be sub-divided into a plurality of
three or more beams which form illuminated areas arranged at
intervals on a circle or other closed geometric figure on the
region.
[0101] Having thus described the invention with particular
reference to the preferred forms thereof, it will be obvious that
various changes and modifications can be made therein without
departing from the spirit and scope of the present invention as
defined by the appended claims.
* * * * *